This invention relates to a process for producing a printed wiring board having fine patterns thereon, particularly to a process for producing a printed wiring substrate by a pattern copper plating method without using a chlorine-containing organic solvent as a developer and easy for peeling a plating resist used therein.
In the production of printed wiring substrates, there have been used resist materials, which are used as plating resists for fine pattern formation in a pattern plating method, suitable for development with a chlorine-containing developer such as 1,1,1-trichloroethane. Such a process for producing a printed wiring board is disclosed, for example, in a report "Resist for Photo-additive Printed Wiring Boards", by K. Masui et al, in "Printed Circuit World Convention IV, Technical Paper WC 1V-68, Jun. 2 to 5 (1987)".
But in such a prior art technique, when an alkali-soluble plating resist is used in the case of conducting chemical copper plating as pattern copper plating, there arises a problem in that resistance to plating solution is poor since said chemical copper plating bath is strongly alkaline (pH 12-13), that is, resistance to plating bath is poor. Such a problem can almost be solved by conducting a curing treatment of the film after resist pattern formation. But in a semiadditive process, when the plating resist is subjected to the curing treatment, removal of the plating resist after formation of etching resist on patterned copper plating becomes very difficult.
When a plating resist suitable for developing with 1,1,1-trichloroethane is used, the problems of the poor resistance to plating bath and the removal of resist can be solved. But the use of 1,1,1-trichloroethane causes a problem of the depletion of the earth's protective ozone layer.